We’ll give the president this much: Even after making major announcements about U.S. forces in Syria, no one really knows what he will do there in the coming year. In terms of keeping the enemy off-balance, we can support the president. After all, one way to win a military campaign is to keep the other side guessing.

There is, however, another aspect of President Donald Trump’s leadership in the Syrian conflict and the war on terror more broadly that hasn’t gotten the attention it deserves. Namely, U.S. presidents carry a unique burden in wartime. While Congress is charged with declaring war, it falls to the president to wage military conflicts.

While Congress has to approve any funding for military campaigns, it is the president who must build the team that can win the war. And while it is up to Congress to conduct oversight of the executive branch, it falls to the president — who has the biggest bullhorn — to make the case to the American people as to how and why military campaigns should proceed.

Trump didn’t launch the United States into war, but he is a wartime president. And, yes, that means that he must make the moral case for war or for withdrawing from the conflicts that we are engaged in. That responsibility doesn’t disappear once a war is joined; it continues for as long as American military servicemen and -women are in harm’s way. We would argue that, in fact, the president’s responsibility in this regard increases after the shooting starts because it is then that our society must support our troops.

In our case, the shooting in the global war on terror started a long time ago, on a different president’s watch. It’s been more than 17 years since 19 hijackers used four jetliners to attack the United States on our home soil. They succeeded at killing some 3,000 people and in provoking a peaceful nation into addressing what had long been a festering wound on humanity — terrorist cells using violence and threat of violence against civilians to achieve political aims.

With the hindsight of history, it seems clear that Osama bin Laden and his terrorist brethren believed that their attacks on 9/11 would show the United States to be a paper tiger, a pushover. And with that fact demonstrated to the world, al-Qaeda would be strengthened as it threatened regimes in far-flung and desperate parts of the world into advancing a tyrannical caliphate.

Instead, the United States reacted by toppling the Taliban regime that had played host to al-Qaeda and spent years hunting down terrorists. And the U.S. did something else that was critically important. Once the Taliban fell, the American government needed to have an opinion about what would follow it. Rather than a strongman, the U.S. supported the people of Afghanistan as they built a democratic government that would expand and protect women’s rights, focus on the well-being of its people and support international norms for how nations interact with each other.

This approach is often derided as nation-building or dismissed as “imposing” our values on other societies. In reality, it is an approach with moral and practicable imperatives. There are no people in the world who desire oppression. So by supporting democracy abroad, the United States can give moral purpose to its work while also giving millions of people across the globe a compelling reason to join our fight against those who would bring terrorism to our shores.

Similarly, the sacrifices made to support democracy in Iraq demonstrated America’s commitment to this work. It also showed something else: That even in the face of protracted warfare, the United States is not a nation than can be cowed. Americans can disagree with the decisions involved in launching these wars. In fact, many have and continue to do so in vigorous public debates.

And that brings us to Trump. In recent days he has mocked allies that have dispatched troops to stand alongside the United States in Afghanistan and seemed to indicate he thinks the Soviet Union was justified in invading Afghanistan in 1979. Those comments are so off-base that it is fair to wonder if he said them just to enflame public debate. Add these comments to his flip-flopping on Syria, and we believe it is past time for the president to make his case to the nation on his strategy for using the American military abroad.

Count us among those who are relieved that the president is now going to slow-walk removing troops from Syria. But these decisions — whether to wage war or whether to withdraw — aren’t ones that should be made on the fly. Lives are at stake, both our soldiers and our citizens who face attacks at home if terrorist organizations aren’t knocked back on their heels.

So we would ask, does the president see us locked in a struggle over ideas, where liberty and tyranny are at each other’s throats? What is his plan for engaging the world and enlisting others to push back against those who would do us harm? Does he see a larger moral purpose in how we conduct ourselves abroad? None of these questions necessitates keeping troops in Syria. But how they are answered have real consequences in terms of building credibility and enhancing American influence across the world, and they can determine how and whether Americans will support the president’s strategy.

Democracies are funny about war. Even when there is strong public support at the start, democratic societies tend not to favor protracted military campaigns. At some point, the sacrifices become too great and large numbers of people begin to ask whether our aims are worth the price we are paying. This has been true for every military conflict in our history. And it is true now as we engage in Afghanistan, Iraq, Syria and other places.

At some point the American public will tire of the fighting. In fact, there is a large constituency in the country that would prefer to simply pull back from world affairs. That constituency will only grow if more Americans conclude that Trump doesn’t know what he wants to do in Syria or any other place where our troops are deployed. If that occurs, it will only grow harder to put American soldiers in harm’s way, even if that is what is required to keep Americans safe.

So now, more than 17 years into the war on terror, it falls to Trump to make his case. What is his strategy for rallying the country and protecting Americans from attack?